Hybrid and electric motors provide an alternative to conventional means of vehicular motive power by either supplementing (in the case of hybrid vehicles) or completely replacing (in the case of electric vehicles) a traditional internal combustion engine (ICE). One form of such alternative vehicle is known as an extended range electric vehicle (EREV). In one embodiment of the EREV, primary electric drive is achieved with a battery that acts as a direct current (DC) voltage source to a motor, generator or transmission that in turn can be used to provide the energy needed to rotate one or more of the vehicle's wheels. Once the electrical charge from the battery has been depleted, backup power may come from an ICE to provide auxiliary onboard electrical energy generation. The Chevrolet Volt is an EREV being manufactured by the Assignee of the present invention.
Various battery architectures may be employed to provide motive or related power to an EREV, including nickel-metal hydride batteries, lead acid batteries, lithium polymer batteries and lithium-ion batteries. Of these, the lithium-ion battery appears to be particularly promising for vehicular applications. One consideration, irrespective of the battery form, is removal of excess heat generated by the electrochemical reaction taking place within the battery during operation. Current battery internal heat exchangers require numerous components and sealing connections, as well as complicated manufacturing processes.
One known method for cooling battery cells is to bring two cells into face contact with a cooling fin through which coolant flows. The cooling fins are connected by integrating an inlet and outlet header hole on both sides of the fin. The inlet and outlet headers are then formed by stacking two or more fins together, and connecting the inlet and outlet header holes. An o-ring seal (or similar seal) may be used to form the seal between two fins. The seals for both inlet and outlet are typically integrated into a frame, which holds the cells and fins in place in the stack. An example of this type of system is shown in FIG. 1 where an expanded view of a battery pack 10 is shown. Individual battery cells 15 are separated by cooling fins 20 such that heat generated by the battery cells 15 is conducted into the cooling fins 20. The cooling fins 20 include a cooling inlet 25 on one side and a cooling outlet 30 on the other with channels 35 to fluidly couple the inlet 25 to the outlet 30. Two battery cells 15 and a cooling fin 20 can be contained in a frame 40. There are seals 45 on both sides of the cooling fin 20 for the cooling inlet 25 and cooling outlet 30; these seals 45 may be integrated into the frame 40 or formed separately and attached subsequently. In addition to the seals 45, this arrangement requires multiple components, as well as a complicated assembly process.